Conventionally, X-ray images using films have been widely used in medical settings. However, an X-ray image using a film provides analog image information. Then, in recent years, digital-mode radiation detectors, such as computed radiography (CR) and flat panel radiation detectors (FPDs), have been developed.
In an FPD, a scintillator panel is used for converting a radioactive ray to visible light. A scintillator panel contains an X-ray phosphor such as cesium iodide (CsI). The X-ray phosphor emits visible light in response to the applied X-ray, and the emitted light is converted into an electric signal by a thin film transistor (TFT) or a charge-coupled device (CCD) to thereby convert the information of the X-ray to digital image information. However, an FPD has a problem that the S/N ratio is small. This is attributable to the scattering of the visible light by the phosphor itself upon the emission of light from the X-ray phosphor, and the like. For the purpose of reducing the influences of this light scattering, methods in which a phosphor is filled in cells divided by a barrier rib have been proposed (Patent Documents 1 to 4).
As a conventional method for forming such a barrier rib, a method in which a silicon wafer is processed by etching is known. In this method, however, the size of a scintillator panel that can be formed is restricted by the size of the silicon wafer, and therefore it is impossible to produce a scintillator panel having a large size of, for example, 500 mm square. On the other hand, a technique for manufacturing a scintillator panel using a glass powder-containing paste is also known, in which the scintillator panel is manufactured by processing a barrier rib, which mainly contains a low-softening-point glass containing 2 to 20% by mass of an alkali metal oxide, over a wide area and with high precision (Patent Document 4).